mc13783_ts.c

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/*
 * Driver for the Freescale Semiconductor MC13783 touchscreen.
 *
 * Copyright 2004-2007 Freescale Semiconductor, Inc. All Rights Reserved.
 * Copyright (C) 2009 Sascha Hauer, Pengutronix
 *
 * Initial development of this code was funded by
 * Phytec Messtechnik GmbH, http://www.phytec.de/
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 */
#include <linux/platform_device.h>
#include <linux/mfd/mc13783.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/input.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/init.h>

#define MC13783_TS_NAME "mc13783-ts"

#define DEFAULT_SAMPLE_TOLERANCE 300

static unsigned int sample_tolerance = DEFAULT_SAMPLE_TOLERANCE;
module_param(sample_tolerance, uint, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(sample_tolerance,
        "If the minimal and maximal value read out for one axis (out "
        "of three) differ by this value (default: "
        __stringify(DEFAULT_SAMPLE_TOLERANCE) ") or more, the reading "
        "is supposed to be wrong and is discarded.  Set to 0 to "
        "disable this check.");

struct mc13783_ts_priv {
    struct input_dev *idev;
    struct mc13xxx *mc13xxx;
    struct delayed_work work;
    struct workqueue_struct *workq;
    unsigned int sample[4];
    struct mc13xxx_ts_platform_data *touch;
};

static irqreturn_t mc13783_ts_handler(int irq, void *data)
{
    struct mc13783_ts_priv *priv = data;

    mc13xxx_irq_ack(priv->mc13xxx, irq);

    /*
     * Kick off reading coordinates. Note that if work happens already
     * be queued for future execution (it rearms itself) it will not
     * be rescheduled for immediate execution here. However the rearm
     * delay is HZ / 50 which is acceptable.
     */
    queue_delayed_work(priv->workq, &priv->work, 0);

    return IRQ_HANDLED;
}

#define sort3(a0, a1, a2) ({                        \
        if (a0 > a1)                        \
            swap(a0, a1);                   \
        if (a1 > a2)                        \
            swap(a1, a2);                   \
        if (a0 > a1)                        \
            swap(a0, a1);                   \
        })

static void mc13783_ts_report_sample(struct mc13783_ts_priv *priv)
{
    struct input_dev *idev = priv->idev;
    int x0, x1, x2, y0, y1, y2;
    int cr0, cr1;

    /*
     * the values are 10-bit wide only, but the two least significant
     * bits are for future 12 bit use and reading yields 0
     */
    x0 = priv->sample[0] & 0xfff;
    x1 = priv->sample[1] & 0xfff;
    x2 = priv->sample[2] & 0xfff;
    y0 = priv->sample[3] & 0xfff;
    y1 = (priv->sample[0] >> 12) & 0xfff;
    y2 = (priv->sample[1] >> 12) & 0xfff;
    cr0 = (priv->sample[2] >> 12) & 0xfff;
    cr1 = (priv->sample[3] >> 12) & 0xfff;

    dev_dbg(&idev->dev,
        "x: (% 4d,% 4d,% 4d) y: (% 4d, % 4d,% 4d) cr: (% 4d, % 4d)\n",
        x0, x1, x2, y0, y1, y2, cr0, cr1);

    sort3(x0, x1, x2);
    sort3(y0, y1, y2);

    cr0 = (cr0 + cr1) / 2;

    if (!cr0 || !sample_tolerance ||
            (x2 - x0 < sample_tolerance &&
             y2 - y0 < sample_tolerance)) {
        /* report the median coordinate and average pressure */
        if (cr0) {
            input_report_abs(idev, ABS_X, x1);
            input_report_abs(idev, ABS_Y, y1);

            dev_dbg(&idev->dev, "report (%d, %d, %d)\n",
                    x1, y1, 0x1000 - cr0);
            queue_delayed_work(priv->workq, &priv->work, HZ / 50);
        } else
            dev_dbg(&idev->dev, "report release\n");

        input_report_abs(idev, ABS_PRESSURE,
                cr0 ? 0x1000 - cr0 : cr0);
        input_report_key(idev, BTN_TOUCH, cr0);
        input_sync(idev);
    } else
        dev_dbg(&idev->dev, "discard event\n");
}

static void mc13783_ts_work(struct work_struct *work)
{
    struct mc13783_ts_priv *priv =
        container_of(work, struct mc13783_ts_priv, work.work);
    unsigned int mode = MC13XXX_ADC_MODE_TS;
    unsigned int channel = 12;

    if (mc13xxx_adc_do_conversion(priv->mc13xxx,
                mode, channel,
                priv->touch->ato, priv->touch->atox,
                priv->sample) == 0)
        mc13783_ts_report_sample(priv);
}

static int mc13783_ts_open(struct input_dev *dev)
{
    struct mc13783_ts_priv *priv = input_get_drvdata(dev);
    int ret;

    mc13xxx_lock(priv->mc13xxx);

    mc13xxx_irq_ack(priv->mc13xxx, MC13XXX_IRQ_TS);

    ret = mc13xxx_irq_request(priv->mc13xxx, MC13XXX_IRQ_TS,
        mc13783_ts_handler, MC13783_TS_NAME, priv);
    if (ret)
        goto out;

    ret = mc13xxx_reg_rmw(priv->mc13xxx, MC13XXX_ADC0,
            MC13XXX_ADC0_TSMOD_MASK, MC13XXX_ADC0_TSMOD0);
    if (ret)
        mc13xxx_irq_free(priv->mc13xxx, MC13XXX_IRQ_TS, priv);
out:
    mc13xxx_unlock(priv->mc13xxx);
    return ret;
}

static void mc13783_ts_close(struct input_dev *dev)
{
    struct mc13783_ts_priv *priv = input_get_drvdata(dev);

    mc13xxx_lock(priv->mc13xxx);
    mc13xxx_reg_rmw(priv->mc13xxx, MC13XXX_ADC0,
            MC13XXX_ADC0_TSMOD_MASK, 0);
    mc13xxx_irq_free(priv->mc13xxx, MC13XXX_IRQ_TS, priv);
    mc13xxx_unlock(priv->mc13xxx);

    cancel_delayed_work_sync(&priv->work);
}

static int __init mc13783_ts_probe(struct platform_device *pdev)
{
    struct mc13783_ts_priv *priv;
    struct input_dev *idev;
    int ret = -ENOMEM;

    priv = kzalloc(sizeof(*priv), GFP_KERNEL);
    idev = input_allocate_device();
    if (!priv || !idev)
        goto err_free_mem;

    INIT_DELAYED_WORK(&priv->work, mc13783_ts_work);
    priv->mc13xxx = dev_get_drvdata(pdev->dev.parent);
    priv->idev = idev;
    priv->touch = dev_get_platdata(&pdev->dev);
    if (!priv->touch) {
        dev_err(&pdev->dev, "missing platform data\n");
        ret = -ENODEV;
        goto err_free_mem;
    }

    /*
     * We need separate workqueue because mc13783_adc_do_conversion
     * uses keventd and thus would deadlock.
     */
    priv->workq = create_singlethread_workqueue("mc13783_ts");
    if (!priv->workq)
        goto err_free_mem;

    idev->name = MC13783_TS_NAME;
    idev->dev.parent = &pdev->dev;

    idev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
    idev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
    input_set_abs_params(idev, ABS_X, 0, 0xfff, 0, 0);
    input_set_abs_params(idev, ABS_Y, 0, 0xfff, 0, 0);
    input_set_abs_params(idev, ABS_PRESSURE, 0, 0xfff, 0, 0);

    idev->open = mc13783_ts_open;
    idev->close = mc13783_ts_close;

    input_set_drvdata(idev, priv);

    ret = input_register_device(priv->idev);
    if (ret) {
        dev_err(&pdev->dev,
            "register input device failed with %d\n", ret);
        goto err_destroy_wq;
    }

    platform_set_drvdata(pdev, priv);
    return 0;

err_destroy_wq:
    destroy_workqueue(priv->workq);
err_free_mem:
    input_free_device(idev);
    kfree(priv);
    return ret;
}

static int __devexit mc13783_ts_remove(struct platform_device *pdev)
{
    struct mc13783_ts_priv *priv = platform_get_drvdata(pdev);

    platform_set_drvdata(pdev, NULL);

    destroy_workqueue(priv->workq);
    input_unregister_device(priv->idev);
    kfree(priv);

    return 0;
}

static struct platform_driver mc13783_ts_driver = {
    .remove     = __devexit_p(mc13783_ts_remove),
    .driver     = {
        .owner  = THIS_MODULE,
        .name   = MC13783_TS_NAME,
    },
};

static int __init mc13783_ts_init(void)
{
    return platform_driver_probe(&mc13783_ts_driver, &mc13783_ts_probe);
}
module_init(mc13783_ts_init);

static void __exit mc13783_ts_exit(void)
{
    platform_driver_unregister(&mc13783_ts_driver);
}
module_exit(mc13783_ts_exit);

MODULE_DESCRIPTION("MC13783 input touchscreen driver");
MODULE_AUTHOR("Sascha Hauer <[email protected]>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:" MC13783_TS_NAME);